The Molecular Biology Core provides NIEHS Center investigators with a variety of services and technical support in the area of recombinant DNA techniques. These include: 1) plasmid DNA production; 2) phage DNA purification, 3) oligonucleotide synthesis; 4) automated DNA sequencing and analysis; 5) transformation of E. coli with plasmid DNA and sequencing of the antibiotic-resistant colonies; 6) competent E. coli cells; 7) restriction digestion and DNA fragment purification; 8) vector and plasmid construction; 9) site-directed mutagenesis; 10) bacterial expression of cDNA derived proteins; 11) isolation of DNA and RNA, Southern and Northern hybridization; 12) polymerase chain reaction; and 13) plasmid vector. In addition, the Molecular Biology Core maintains a collection of vectors, genomic and cDNA libraries. The Molecular Biology Core is strategically placed to provide easy access to NIEHS Center investigators. Most of the investigators used the Molecular Biology Core facility. Among the various services, two services (DNA synthesis and DNA sequencing) were maximally used. Two other services (competent cells and plasmid preparations) were also frequently used. The other facilities were also used but at much lower frequency. The use of oligonucleotide synthesis and DNA sequencing facilities showed increasing trend during the initial four years of the grant. The Molecular Biology Core facility provided service support to NIEHS Center investigators in completion of their research goals, publication of results and obtaining new grants and renewal of grants. A total of 102 manuscripts and 29 grants have received services and technical support from the Molecular Biology Core. The Molecular Biology Core has plans to increase its capacity for DNA synthesis and DNA sequencing during the next funding period. The acquisition of a second 310 Genetic Analyzer will accommodate an additional 130 sequence reactions per week. The Molecular Biology Core will also replace its current 394 DNA synthesizer with an Applied Biosystems Model 3948 Nucleic Acid Synthesis and Purification System. It will increase the Molecular Biology Core?s capacity from 12 to 48 primers per day. The investigators paid 50% of the supply to the Molecular Biology Core to obtain services. Organization of the Molecular Biology Core included request forms and product data sheets. In addition, the Molecular Biology Core provided protocols, consultation and advise to the post-doctoral fellows, graduate students, and scientific technicians.